Spar inspection before closure has not been required for many years now but I'd still take the advise of earlier post and get another set of trained eyes to inspect them to the point possible. If the spar is completely closed, you might be able to drill a small diameter hole in the very end (dead center) and inspect the first bay with one of those bore scopes used to inspect engine cylinders. If the inside of the first bay looks good you can probably assume the rest of the spar is of equal quality. Verify to your level of comfort.
Larry Flesner
